grounded direct bury aluminum conductors

[electrofelon]

Do you think grounded conductors are much less prone to failure than ungrounded ones? Have you even seen a failed direct buried aluminum grounded conductor? I always assumed ungrounded conductors are so prone to failure because of the electrolysis that happens every half cycle making oxygen at any point of compromised insulation. Would a grounded conductor having presumably only a few volts of potential to the dirt last a lot longer?

 

[peter d]

Good question. I'm not smart enough to answer that one, other than to say I never direct bury anything in this area. Way too many rocks in the ground.

 

[LarryFine]

Of the residential trouble-shooting calls I've gone on that ended up involving loss of an underground service conductor, it has been the neutral just about every time.

 

[Jon456]

From what I've seen, I'd never put any aluminum conductors below grade (either direct-buried or in conduit).

 

[electrofelon]

Of the residential trouble-shooting calls I've gone on that ended up involving loss of an underground service conductor, it has been the neutral just about every time.

interesting, well your experience blows my theory out of the water. Ive seen a bunch of direct bury failures in my career, but only a few that I got to see the problem. Of those, I dont recall which conductor it was.

This is just an academic question, I am super not a fan of direct bury.

 

[electrofelon]

Perhaps an experiment is in order......

 

[ptonsparky]

Direct bury Al is very common. We find most of our problems being the phase conductors because in Ag, the neutral is not required for operation. That said, once we get into testing, the neutral often needs repairs as well.

Residential? I’m not sure if either is more prevalent.

We almost always use PVC, but some of that direct bury has been in the ground for 40 years. Hard to argue with that.

 

[LarryFine]

We find most of our problems being the phase conductors because in Ag, the neutral is not required for operation.

Ag?

 

[Dzboyce]

Agriculture, as in farming

 

[Cow]

Direct bury Al is very common. We find most of our problems being the phase conductors because in Ag, the neutral is not required for operation. That said, once we get into testing, the neutral often needs repairs as well.

Residential? I’m not sure if either is more prevalent.

We almost always use PVC, but some of that direct bury has been in the ground for 40 years. Hard to argue with that.

Our experience has been the same.

 

[romex jockey]

Perhaps an experiment is in order......

Now I wonder if southwire,or other manufacturers have ventured to do so?

~RJ~

 

[electrofelon]

Direct bury Al is very common. We find most of our problems being the phase conductors because in Ag, the neutral is not required for operation. That said, once we get into testing, the neutral often needs repairs as well.

Residential? I’m not sure if either is more prevalent.

We almost always use PVC, but some of that direct bury has been in the ground for 40 years. Hard to argue with that.

Our experience has been the same.

In those cases had the neutral failed substantially or completely, or just failed a megger test but was still working?

 

[ptonsparky]

In those cases had the neutral failed substantially or completely, or just failed a megger test but was still working?

A bit of both. We can literally find pin holes in the insulation, when the conditions are right, and well before the Al rots away.

A phase conductor fault can turn the surrounding soil into glass so obviously they have more damage and do more damage to the adjacent conductors.

 

[peter d]

Always use conduit/raceway.

 

[ptonsparky]

Always use conduit/raceway.

That helps considerably.

Floods this spring covered a pump motor and PP. These were feed lot manure lagoons so nasty stuff. Conduit was filled and when we megged, 3 @ 100 M, 1@1M. Even though it came up to 1054 volts we failed it. Grounded Delta 480v. Wires won’t move due to the added stuff. Everything is now abandoned.

 

[Jon456]

Always use conduit/raceway.

That helps considerably.

It helps even more if the installers don't damage the insulation while pulling the conductors into the conduit. :slaphead:

 

[ptonsparky]

It helps even more if the installers don't damage the insulation while pulling the conductors into the conduit. :slaphead:

Or the conductor isn't flawed.on the way in. Seen it more than once.

 

[ActionDave]

Or the conductor isn't flawed.on the way in. Seen it more than once.

Re feeding the filter building at the water treatment plant at midnight came across a wrinkled up, ugly, busted up section if insulation as it came off the reel. There was no going back to the supply house at that hour and the plant had to go back online in the morning......

We taped up the wire and alternated coats of scotch kote between layers. It's held up for over ten years now.

 

[ptonsparky]

...

We taped up the wire and alternated coats of scotch kote between layers. It's held up for over ten years now.

Just what we do. Did we go to different schools together?

 

[ActionDave]

Just what we do. Did we go to different schools together?

I think so. I'm sure you graduated before I did.